Designation: E2126 – 11
Standard Test Methods for
Cyclic (Reversed) Load Test for Shear Resistance of Vertical
Elements of the Lateral Force Resisting Systems for
Buildings 1
This standard is issued under the fixed designation E2126; the number immediately following the designation indicates the year of
original
origin
al adoption or, in the case of revis
revision,
ion, the year of last revision.
revision. A number in paren
parenthese
thesess indicates the year of last reappr
reapproval.
oval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Sco
Scope
pe
1.1 The
These
se test methods
methods cov
cover
er the evaluatio
evaluation
n of the she
shear
ar
stiffness, shear strength, and ductility of the vertical elements
of lateral force resisting systems, including applicable shear
connections
connec
tions and holdhold-down
down conne
connections
ctions,, under quasi-static
cyclic (rever
(reversed)
sed) load condi
conditions.
tions.
1.2 These test methods
methods are int
intend
ended
ed for specimens
specimens con
con-struc
str
ucted
ted fr
from
om wo
wood
od or me
metal
tal fr
fram
amin
ing
g br
brac
aced
ed wi
with
th so
solid
lid
sheathing or other methods or structural insulated panels.
1.3 The values stated in inch-poun
inch-pound
d units are to be regar
regarded
ded
as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only
and are not considered standard.
standard
d doe
doess not purport
purport to add
addre
ress
ss all of the
1.4 This standar
safet
sa
fetyy co
conc
ncer
erns
ns,, if an
anyy, as
asso
socia
ciate
ted
d wit
with
h its us
use.
e. It is th
thee
responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenc
Referenced
ed Documents
Documents
2.1 ASTM Standards: 2
D2395 T
Test
est Met
Method
hodss for Spe
Specifi
cificc Gra
Gravit
vity
y of Wood and
Wood-Based Materials
D4442 Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base Materials
D4444 T
Test
est Met
Method
hod for Lab
Labora
orator
tory
y Sta
Standa
ndardi
rdizati
zation
on and
Calibration of Hand-Held Moisture Meters
E564 Practice for Static Load Test for Shear Resistance of
Framed Walls for Buildings
E575 Practice for Reporting Data from Structural Tests of
Building
Buildi
ng Constr
Construction
uctions,
s, Elemen
Elements,
ts, Conne
Connections
ctions,, and Assemblies
1
These test methods are under the jurisdiction of ASTM Committee E06 on
Performance of Buildings and are the direct responsibility of Subcommittee E06.11
on Horizontal and Vertical Structures/Structural Performance of Completed Structures.
Curren
Cur
rentt edi
editio
tion
n app
approv
roved
ed May 1, 201
2011.
1. Pub
Publis
lished
hed May 201
2011.
1. Orig
Origina
inally
lly
approved in 2001. Last previous edition approved in 2010 as E2126 – 10. DOI:
10.1520/E2126-11.
2
For refere
referenced
nced ASTM stand
standards,
ards, visit the ASTM websi
website,
te, www
www.astm
.astm.org
.org,, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
E631 Terminology of Building Constructions
Standard:3
2.2 ISO Standard:
ISO 16670 Timber Structures—Joints Made with Mechanical Fasteners—Quasi-static Reversed-cyclic Test Method
Standards:4
2.3 Other Standards:
ANSI/AF&PA NDS Na
Natio
tional
nal Des
Design
ign Spe
Specifi
cificat
cation
ion for
Wood Construction
3. Terminology
3.1 For de
3.1
defin
finiti
ition
onss of te
term
rmss us
used
ed in th
this
is sta
stand
ndar
ard,
d, se
seee
Terminology E631
E631..
3.2 Definitions of Terms Specific to This Standard:
3.2.1 ductility ratio, cyclic (D), n —the ratio of the ultimate
displacement
displa
cement (Du) an
and
d th
thee yi
yield
eld di
disp
splac
lacem
emen
entt (Dyield) o f a
specimen observed in cyclic test.
3.2.2 elastic shear stiffness (K e) (see 9.1.4
9.1.4,, Fig. 1)
1), n—the
resistance to deformation of a specimen in the elastic range
before the first major event (FME) is achieved, which can be
expressed
expre
ssed as a slope measured
measured by the ratio of the resisted shear
load to the corresponding displacement.
3.2.3 envelope curve (see Fig. 2),
2), n —the locus of extremities of the load-displacement hysteresis loops, which contains
the peak loads from the first cycle of each phase of the cyclic
loading and neglects points on the hysteresis loops where the
absolute value of the displacement at the peak load is less than
that in the previous phase.
3.2.3.1 Discussion—Specim
—Specimen
en displa
displacement
cement in the positi
positive
ve
directi
dir
ection
on pro
produc
duces
es a pos
positiv
itivee env
envelop
elopee cur
curve;
ve; the neg
negativ
ativee
specimen
specim
en displa
displacement
cement produces a negativ
negativee envelo
envelope
pe curve.
The positive direction is based on outward movement of the
hydraulic actuator.
envelope
lope curve, avera
average
ge (see Fi
3.2.4 enve
Fig.
g. 3), n—envelope
curve obtained by averaging the absolute values of load and
displacement of the corresponding positive and the negative
envelope points for each cycle.
equivalent
lent ener
energy
gy elasticelastic-plastic
plastic (EEEP) curve (see
3.2.5 equiva
9.1.4,, Fig. 1),
9.1.4
1), n —an ideal elasticelastic-plastic
plastic curve circum
circumscribin
scribing
g
3
Available from International Organization for Standardization (ISO), 1, ch. de
la Voie
oie-Cr
-Creus
euse,
e, Cas
Casee pos
postal
talee 56, CHCH-121
1211,
1, Gen
Geneva
eva 20, Swi
Switze
tzerla
rland,
nd, htt
http:/
p:///
www.iso.ch.
4
Available from American Forest and Paper Association (AF&PA), 1111 19th
St., NW, Suite 800, Washington, DC 20036, http://www.afandpa.org.
Copyright. (C) ASTM International, 100 Barr Harbor Drive, PO Box C-700 West Conshohocken, Pennsylvania 19428-2959, United States
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E2126 – 11
FIG. 1 Performance Parameters of Specimen: (A) Last Point at
an area equal to the area enclosed by the envelope curve
between the origin, the ultimate displacement, and the displacement axis. For monotonic tests, the observed loaddisplacement curve is used to calculate the EEEP curve.
3.2.6 failure limit state, n —the point on the envelope curve
corresponding to the last data point with the absolute load
equal or greater than |0.8 Ppeak|, as illustrated in Fig. 1.
3.2.7 failure load (Pu), n—the load corresponding to the
failure limit state.
3.2.8 first major event (FME) , n—the first significant limit
state to occur (see limit state).
3.2.9 limit state, n —an event that demarks the two behavior
states, at which time some structural behavior of the specimen
is altered significantly.
3.2.10 specimen, n —the vertical element of the lateral force
resisting system to be tested. Example of specimens are walls,
structural insulated panels, portal frames, etc. A specimen can
be a single element or an entire line of resistance within a
lateral force resisting system.
3.2.11 stabilized response, n—load resistance that differs
not more than 5 % between two successive cycles at the same
amplitude.
3.2.12 strength limit state (see Fig. 1), n —the point on the
envelope curve corresponding to the maximum absolute displacement D peak at the maximum absolute load ( Ppeak) resisted
by the specimen.
Pu
$
0.8 P peak
3.2.13 ultimate displacement, cyclic (Du), n—the displacement corresponding to the failure limit state in cyclic test.
3.2.14 ultimate displacement, monotonic ( Dm), n—the displacement corresponding to the failure limit state in monotonic
test.
3.2.15 yield limit state, n —the point in the loaddisplacement relationship where the elastic shear stiffness of
the assembly decreases 5 % or more. For specimens with
nonlinear ductile elastic response, the yield point ( Dyield, P yield)
is permitted to be determined using the EEEP curve (see 9.1.4).
4. Summary of Test Method
4.1 The elastic shear stiffness, shear strength and ductility of
specimens are determined by subjecting a specimen to fullreversal cyclic racking shear loads. This is accomplished by
anchoring the bottom edge of the specimen to a test base
simulating intended end-use applications and applying a force
parallel to the top of the specimen. The specimen is allowed to
displace in its plane. Sheathing panels that are a component of
a specimen shall be positioned such that they do not bear on the
test frame during testing. (See Note 1.) As the specimen is
racked to specified displacement increments, the racking
(shear) load and displacements are continuously measured (see
8.7).
NOTE 1—If the end-use applications require sheathing panels bear
directly on the sill plate, such as most structural insulated panels, the
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E2126 – 11
FIG. 1 Performance Parameters of Specimen: (B) Last Point at
Pu
= 0.8 P peak (continued)
FIG. 2 Examples of Observed Hysteresis Curve and Envelope Curves for Test Method A
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E2126 – 11
FIG. 2 Examples of Observed Hysteresis Curve and Envelope Curves for Test Method B (continued)
specimen may be tested with sheathing panels that bear on the sill plate.
5. Significance and Use
5.1 These test methods are intended to measure the performance of vertical elements of the lateral force resisting system
subjected to earthquake loads. Since these loads are cyclic, the
loading process simulates the actions and their effects on the
specimens.
6. Specimen
6.1 General—The typical specimen consists of a frame,
bracing elements, such as panel sheathing, diagonal bracing,
etc., and fastenings. The bracing is attached on one side of the
frame unless the purpose of the test requires bracing on both
sides. The elements of the specimen shall be fastened to the
frame in a manner to conform to 6.2. Elements used to
construct specimens may be varied to permit anticipated failure
of selected elements. All detailing shall be clearly identified in
the report in accordance with Section 10.
6.2 Connections—The performance of specimens is influenced by the type, spacing, and edge distance of fasteners
attaching sheathing to framing and spacing of the shear
connections and hold-down connectors, if applicable, and the
tightness of the fasteners holding the specimen to the test base.
6.2.1 Sheathing Panel Attachments —All panel attachments
shall be consistent with the types used in actual building
construction. Structural details, such as fastener schedules,
fastener edge distance, and the gap between panels, shall be
reported in accordance with Section 10.
6.2.2 Attachment to the Test Base—Specimen shall be
attached to the test base with fasteners in a manner representing
field conditions. For intended use requirements over a nonrigid foundation, a mock-up flexible base shall be constructed
to simulate field conditions. Consideration shall be given to the
orientation and type of floor joists relative to the orientation of
the wall assembly. When strap connections are used, they shall
be installed (that is, inside/outside the sheathing, etc.) without
pre-tension in a configuration that simulates the field application. The test report shall include details regarding this attachment.
6.2.3 Anchor and Hold-Down Bolts —When the specimen
frame is made of solid wood or wood-based composites, the
anchor bolts shall be tightened to no more than finger tight plus
a 1 ⁄8 turn, provided that the design value of stress perpendicular
to the grain is not exceeded (see Note 2). The hold-down bolts
shall be tightened consistently between replicates in accordance with hold-down manufacturer’s recommendation. The
assembly test shall not start within 10 min of the anchor bolt
tightening to allow for stress relaxation of the anchor.
NOTE 2—Since solid wood and wood-based composites relax over time
as well as potentially shrink due to changing moisture content, the intent
of the finger tight plus a 1⁄8 turn is to avoid any significant pre-tension on
the anchor bolts, which may affect the test results. It is the committee
judgment that the maximum bolt tension should not be more than 300 lbf
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E2126 – 11
FIG. 2 Examples of Observed Hysteresis Curve and Envelope Curves for Test Method C (continued)
(1.33 kN) for the purpose of ensuring the bolt is not caught on a thread or
not seated fully. It should be noted that, however, the bolt tension depends
on wood species and density, bolt thread pitch (or bolt diameter), and plate
washer size. A general rule of thumb is to finger-tight plus 1⁄8 turn, which
will result in a nut displacement of approximately 0.01 in. (0.254 mm) for
1⁄2 and 5⁄8-in.-diameter (12.7 and 15.9-mm-diameter) UNC bolts. A torque
of about 50 lbf-in. (5.65 kN-mm) without bolt lubrication would normally
produce 300 lbf (1.33 kN) of bolt tension.
6.3 Frame Requirements—The frame of the specimen shall
consist of materials representative of those to be used in the
actual building construction. The connections of these members shall be consistent with those intended in actual building
construction.
6.3.1 For wood framing members, record the species and
grade of lumber used (or the relevant product identification
information for structural composite lumber framing); moisture
content of the framing members at the time of the specimen
fabrication and testing, if more than 24 h passes between these
operations (see Test Methods D4442, Test Methods A or B; or
D4444, Test Methods A or B); and specific gravity of the
framing members (see Test Methods D2395, Test Method A).
The specific gravity of the framing members shall be representative of the published specific gravity for the product with
no individual member exceeding the published value by more
that 10 % (see ANSI/AF&PA NDS for example).
6.3.2 For steel or other metal framing members, record the
material specifications and thickness.
6.4 Structural Insulated Panel —The panel is prefabricated
assembly consisting of an insulating core of 1.5 in. (38 mm)
minimum sandwiched between two facings. The assembly is
constructed by attaching panels together and to top and bottom
plates or tracks.
6.5 Specimen Size —The specimen shall have a height and
length or aspect (height/length) ratio that is consistent with
intended use requirements in actual building construction (see
Fig. 4).
7. Test Setup
7.1 The specimen shall be tested such that all elements and
sheathing surfaces are observable. For specimens such as
framed walls with sheathing on both faces of framing or
frameless structural insulated panels, the specimens are dismantled after tests to permit observation of all elements.
7.2 The bottom of the specimen shall be attached to a test
base as specified in 6.2. The test apparatus shall support the
specimen as necessary to prevent displacement from the plane
of the specimen, but in-plane displacement shall not be
restricted.
7.3 Racking load shall be applied horizontally along the
plane of the specimen using a double-acting hydraulic actuator
with a load cell. The load shall be distributed along the top of
the specimen by means of a loading beam or other adequate
devices. The beam used to transfer loads between the hydraulic
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E2126 – 11
FIG. 3 Example of Average Envelope Curve (see Fig. 2, Test Method C)
FIG. 4 An Example of Shear Wall Specimen
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E2126 – 11
FIG. 5 An Example of Test Setup for Shear Wall Specimen
cylinder and the test specimen shall be selected so that it does
not contribute to the measured racking strength and stiffness.
7.3.1 If applied to the top of the specimen directly, for
example, as is shown in Fig. 5, the maximum stiffness of load
beam permitted is 330 000 kips-in.2 (947 kN-m 2) (see Note 3).
NOTE 3—The selected stiffness corresponds with an HSS 5 3 3 3
1⁄4-in. (127 3 76 3 6.4-mm) steel section. Other sections with equal or
less stiffness have been successfully employed.
7.3.2 The load beam selected shall not be continuous over
discontinuities in the test specimen (see Note 4).
NOTE 4—Examples of discontinuities include portal frame openings,
wall perforations, transitions between differential bracing types, etc.
Continuation of a rigid load beam over these discontinuities can add to the
measured in-plane rigidity of the system. However, the use of continuous
load beam over discontinuities may be considered provided that the added
in-plane rigidity can be justified by the end-use applications.
7.3.3 The combined gravity load applied to the specimen by
the load beam and actuator shall be less than 350 lbf (1.56 kN),
unless the purpose of the test includes the influence of vertical
loads on the system performance (see Appendix X3).
7.4 Test setup shall be designed and installed so that vertical
(gravity) loads from test equipment applied to the specimen are
negligible. Other vertical loads shall not be added to the
specimen unless justified by analysis of actual building construction or the objective of the testing. When vertical loads are
applied, the magnitude and test setup for the vertical load shall
be reported along with the justification.
NOTE 5—The neglect of vertical loads in this standard may result in
inaccurate estimates of the capacity of the specimen as an element of the
lateral force resisting system in actual building construction. For example,
the neglect of uplift forces in testing may overestimate the racking
capacity of the element, while the neglect of dead weight of the story
above may underestimate the racking capacity of the element unless
buckling is the predominant failure mode.
8. Procedure
8.1 Number of Tests—A minimum of two specimens of a
given construction shall be tested if the shear strength (v peak)
values of each specimen calculated according to 9.1.1 are
within 10 % of each other. The lower of the two test values
shall be used to calculate the 10 % allowance. Otherwise, at
least three specimens of a given construction shall be tested.
8.2 The cyclic displacement of the actuator shall be controlled to follow a cyclic displacement procedure described in
either 8.3 (Test Method A), 8.4 (Test Method B), or 8.5 (Test
Method C).
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E2126 – 11
8.3 Test Method A (Sequential-Phased Displacement Procedure) :
8.3.1 Sequential Phased Displacement (SPD) Loading
Protocol—Displacement-controlled loading procedure that involves displacement cycles grouped in phases at incrementally
increasing displacement levels. The cycles shall form either a
sinusoidal wave or a triangular wave. The SPD loading
consists of two displacement patterns and is illustrated in Fig.
6. The first displacement pattern consists of three phases, each
containing three fully-reversing cycles of equal amplitude, at
displacements representing 25 %, 50 %, and 75 % of anticipated FME. The second displacement pattern is illustrated in
Fig. 7. Each phase is associated with a respective displacement
level and contains one initial cycle, three decay cycles, and a
number of stabilization cycles. For nailed wood-frame walls,
three stabilization cycles are sufficient to obtain a stabilized
response. The amplitude of each consecutive decay cycle
decreases by 25 % of the initial displacement.
8.3.2 The schedule of amplitude increments between the
sequential phases is given in Table 1. The amplitude increments selected for the SPD procedure are based on the FME
determined from the static monotonic load test on an identical
specimen in accordance with Practice E564. To determine
Dyield, it is permitted to compute EEEP curves, as shown in Fig.
1 based on monotonic test data, in accordance with 9.1.4.
8.4 Test Method B (ISO 16670 Protocol) :
8.4.1 I SO
D is pl ac em en t
S ch ed ul e—Displacementcontrolled loading procedure that involves displacement cycles
grouped in phases at incrementally increasing displacement
levels. The ISO loading schedule consists of two displacement
patterns and is illustrated in Fig. 8. The first displacement
pattern consists of five single fully reversed cycles at displacements of 1.25 %, 2.5 %, 5 %, 7.5 %, and 10 % of the ultimate
displacement D m. The second displacement pattern consists of
phases, each containing three fully reversed cycles of equal
amplitude, at displacements of 20 %, 40 %, 60 %, 80 %,
100 %, and 120 % of the ultimate displacement D m.
8.4.2 The sequence of amplitudes, which is given in Table 2,
are a function of the mean value (where applicable) of the
ultimate displacement (Dm) obtained from matched specimens
in the monotonic tests in accordance with Practice E564.
8.5 Test Method C (CUREE Basic Loading Protocol) :
8.5.1 CUREE Basic Loading Protocol—Displacementcontrolled loading procedure that involves displacement cycles
grouped in phases at incrementally increasing displacement
levels. The loading history starts with a series of (six) initiation
cycles at small amplitudes (of equal amplitude). Further, each
phase of the loading history consists of a primary cycle with
amplitude expressed as a fraction (percent) of the reference
deformation, D , and subsequent trailing cycles with amplitude
of 75 % of the primary one.
NOTE 6—The initiation cycles serve to check loading equipment,
measurement devices, and the force-deformation response at small amplitudes.
8.5.2 The schedule of amplitude increments is given in
Table 3 and is illustrated in Fig. 9. The reference deformation
D shall be an estimate of the maximum displacement at which
the load in a primary cycle has not yet dropped below 0.8 Ppeak.
The value of D shall not exceed 0.025 times the wall height. If
the panel has not failed at the end of Phase 8 of Table 3, then
additional phases shall be added. Each subsequent phase shall
consist of a primary cycle with an increase in amplitude of a
(a # 0.5) over the previous primary cycle, and followed by
two trailing cycles with amplitude of 75 % of the primary one.
FIG. 6 Cyclic Displacement Schedule (Test Method A)
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E2126 – 11
FIG. 7 Single Phase of Pattern 2 (Test Method A)
FIG. 8 Cyclic Displacement Schedule (Test Method B)
8.6 The actuator displacement in Test Methods A, B, or C
shall be controlled at either constant cyclic frequency or at a
constant rate of displacement. The rate of displacement shall be
between 0.04 and 2.5 in./s (1.0 and 63.5 mm/s). The cyclic
frequency shall range from 0.2 to 0.5 Hz to avoid inertial
effects of the mass of the wall and test fixture hardware during
cyclic loading. The loading shall follow the corresponding
procedure until the applied load diminishes more than 0.2
Ppeak, that is, until the failure limit state occurs.
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E2126 – 11
FIG. 9 Cyclic Displacement Pattern (Test Method C)
TABLE 1 Test Method A—Amplitudes of Initial Cycles
Pattern
Step
1
1
2
3
4
5
6
7
8
9
10
11
12
2
A
Minimum Number
of CyclesA
Amplitude of Initial Cycle
% FME
3
3
3
7
7
7
7
7
7
7
7
25
50
75
100
125
150
175
200
250
300
350
Additional increments of
50 (until specimen failure)
See 8.3.1 for details.
TABLE 2 Test Method B—Amplitudes of the Reversed Cycles
Pattern
Step
Minimum Number
of Cycles
1
1
2
3
4
5
6
7
8
9
10
11
1
1
1
1
1
3
3
3
3
3
3
2
8.7 Displacements shall be measured with displacement
measuring devices with a resolution of 0.005 in. (0.13 mm) or
Amplitude, % D m
1.25
2.5
5
7.5
10
20
40
60
80
100
Additional increments of
20 (until specimen failure)
other suitable devices for continuously measuring displacement under cyclic loading conditions, at a minimum sampling
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E2126 – 11
TABLE 3 Test Method C—Amplitude of Primary Cycles
Pattern
Step
Minimum Number
of Cycles
Amplitude of Primary
Cycle, % D
1
2
1
2
3
4
5
6
7
8
9
10
6
7
7
4
4
3
3
3
3
3
5
7.5
10
20
30
40
70
100
100 + 100aA
Additional increments of
100a (until specimen failure)
3
4
A
a
#
0.5.
rate of 100 readings per cycle. The following instrumentation
shall be provided for measuring displacements, and hold-down
connector forces when required:
8.7.1 Horizontal displacement of the specimen at the top
plate.
8.7.2 Vertical (upward and downward) displacement of both
end posts (or equivalent) relative to the rigid base. The
reference point for this measurement shall be on or immediately adjacent to the outside face of the end post.
8.7.3 Horizontal displacement of the bottom plate relative to
the rigid base (lateral in-plane sliding).
8.7.4 Vertical displacement of the hold-down connectors
relative to the end posts (deformation of the connectors and
fastener slip), as applicable.
8.7.5 When specified, loads on the bolts fastening the
hold-down connectors to the rigid base.
9. Calculation
9.1 Based on the observed hysteresis response curves, the
envelope (positive and negative) curves are generated for each
tested specimen. If the laboratory chooses to report the positive
and negative performances individually, then both envelopes
(positive and negative) shall be analyzed separately in accordance with Section 9. If the laboratory chooses to report one set
of performance parameters that characterizes both envelopes,
then the positive and negative envelope curves shall be
averaged to produce an average envelope curve according to
3.2.4 and the calculations outlined in Section 9 shall be
conducted for each specimen based up the average envelope
curve.
NOTE 7—If the specimen behavior in the positive and negative quadrants is similar (major events occur in the same phases on the negative and
positive sides), a reasonable approximation of the average performance
can be achieved by determining the parameters from positive and negative
envelopes individually and then averaging them (see Appendix X4).
9.1.1 Shear Strength ( npeak) lbf/ft (N/m)—The maximum
load per unit specimen length resisted by the specimen in the
given envelope shall be calculated as follows:
npeak 5
Ppeak
L
(1)
where:
Ppeak = maximum load resisted by the specimen in the
given envelope, lbf (N); and
L
= length of specimen, ft (m).
9.1.2 Secant shear modulus, G , at 0.4 Ppeak and at Ppeak
shall be calculated as follows:
8
G 5
8
P H
3
L
D
(2)
where:
G = shear modulus of the specimen obtained from test
(includes shear and uplift deformation for the connection system), lbf/in. (N/m); represents the secant shear
stiffness at specified specimen displacements times
the aspect ratio;
P = applied load measured at the top edge of the specimen, lbf (N);
D = displacement of the top edge of the specimen based on
test, in. (m). This includes both the shear deflection of
the sheathing material and its connections, and the
contribution of the shear and hold-down connection
systems;
H = height of specimen, ft (m); and
L = length of specimen, ft (m).
9.1.3 Cyclic ductility ratio, D , as described in 3.2.1, shall be
calculated. If the shear stiffness (shear modulus) at 0.4 P peak is
greater than that at P peak, generate the EEEP curve as described
in 9.1.4. Otherwise, the FME and the ultimate displacement
shall be determined directly from the envelope curve. Calculate
values of displacement, shear forces, and shear modulus at the
yield limit state and strength limit state.
9.1.4 When specified by 9.1.3, develop an EEEP curve to
represent the envelope curve. Fig. 1 illustrates typical EEEP
curve. The elastic portion of the EEEP curve contains the
origin and has a slope equal to the elastic shear stiffness, Ke.
The plastic portion is a horizontal line equal to Pyield determined by the following equation:
8
Pyield 5
If D2u ,
S Œ
Du 2
D2u 2
D
2A
Ke
Ke
(3)
2A
, it is permitted to assume P yield 5 0.85 P peak
Ke
where:
Pyield = yield load, lbf (N);
= the area under envelope curve from zero to ultiA
mate displacement (Du) of the specimen, lbf·in.
(N·m);
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E2126 – 11
Ppeak
= maximum absolute load resisted by the specimen
in the given envelope, lbf (N);
= displacement of the top edge of the specimen at
De
0.4 Ppeak, in. (mm); and
Ke
= 0.4 Ppeak/De.
9.1.4.1 To generate an EEEP curve as described in 8.3.2
based on monotonic test results, the procedures in this section
are permitted, with Dm substituting for Du.
9.1.5 If the envelope curve contains data points at loads less
than |0.8 P peak| (past strength limit state), the failure limit state
shall be determined at 0.8 Ppeak using linear interpolation, as
illustrated in Fig. 1.
10. Report
10.1 The report shall include the following information:
10.1.1 Date of the test and of report.
10.1.2 Names of the test sponsors and test agency and their
locations.
10.1.3 Identification of the specimen (test number, and so
forth).
10.1.4 Detailed description of the specimen and the test
setup, including the following:
10.1.4.1 Dimensions of the specimen.
10.1.4.2 Details of the physical characteristics or structural
design, or both, of the specimen, including, if applicable, the
type, spacing, and edge distance of fasteners attaching sheathing to framing.
10.1.4.3 Details of attachment of the specimen in the test
fixture, including a description of the test base and whether
sheathing panels are directly bearing on the sill plate during
testing.
10.1.4.4 Location of load application and load cell, strain
gauges, deflection gauges, and other items for test as applicable.
10.1.4.5 Description of construction materials (for example,
material type and grade, thickness, yield point, tensile strength,
compressive strength, density, moisture content, manufacturer
of components used, source of supply, dimensions, model,
type, and other pertinent information, and so forth, as appropriate for materials used).
10.1.4.6 Drawing showing plan, elevation, principal cross
section, and other details as needed for description of the
specimen and the test setup (see 10.1.4.1-10.1.4.5).
10.1.4.7 Description of general ambient conditions including the following:
(1) At construction;
(2) During curing or seasoning, if applicable (including
elapsed time from construction to test); and
(3) At test.
10.1.4.8 Modifications made on the specimen during testing.
10.1.4.9 Description of any noted defects existing in the
specimen prior to test.
10.1.5 Description of the test, including a statement that the
test or tests were conducted in accordance with this test method
or otherwise describing any deviations from the test method.
10.1.6 Summary of results, including:
10.1.6.1 Hysteresis loops (applied load versus displacement
at the top of the specimen) for every specimen tested.
10.1.6.2 Complete record (table or plot) of individual displacements required to be measured in 8.7.
10.1.6.3 Shear strength (npeak) from tests of identical specimens (9.1.1).
10.1.6.4 As-tested and mean values of P , D and G at yield
limit state and strength limit state in accordance with Section 9.
10.1.6.5 EEEP curve developed from the mean loads and
displacements at yield limit state and failure limit state, if
applicable (see 9.1.3 and 9.1.4).
10.1.7 Description of failure modes and any behavior
change and significant events, for each test.
10.1.8 Photographs of the specimen, particularly those depicting conditions that cannot otherwise be easily described in
the report text, such as failure modes and crack patterns.
10.1.9 Appendix (if needed) that includes all data not
specifically required by test results. Include special observations for building code approvals.
10.1.10 Signatures of responsible persons are in accordance
with Practice E575.
8
11. Precision and Bias
11.1 No statement on the precision and bias is offered due to
the numerous individual elements that comprise the specimen
and the small number of replicate specimens tested. A generally accepted method for determining precision and bias is
currently unavailable.
12. Keywords
12.1 cyclic loads; earthquake; framed walls; lateral-force
resisting systems; portal frames; racking loads; rigid support;
shear displacement; shear stiffness; shear strength; structural
insulated panels
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E2126 – 11
APPENDIXES
(Nonmandatory Information)
X1. DETERMINATION OF FIRST MAJOR EVENT
X1.1 The FME is the first significant limit state that occurs
during the test. The limit state in turn denotes an event marking
phase change between two behavior states. As noted in 8.3.2,
the FME can be determined from monotonic load tests on an
identical specimen. If the first estimate is inappropriate, the
data obtained can be revised for the subsequent tests. The
following estimates offer guidance for a typical 8-ft (2.4-mm)
wall.
X1.1.1 Wood-Framed Walls with Wood Structural Panel
Sheathing—Aspect ratios of 2:1 or less, FME = 0.8 in. (20
mm); aspect ratio of 4:1, FME = 1.2 in. (31 mm).
X1.1.2 Wood-Framed Walls with Gypsum Sheathing—
Aspect ratios of 2:1 or less, FME = 0.25 in. (6.4 mm).
X2. SELECTION OF CYCLING METHOD
X2.1 Test Method A Versus Test Method B
X2.1.1 Test Method A:
X2.1.1.1 Test Method A is a sequential phased displacement
pattern that exhibits decay cycles between the steps in the
loading pattern. These decay cycles provide information on
whether there is a lower bound in displacement required to
produce hysteretic energy dissipation (1).5 An example where
a lower bound displacement causing hysteretic energy dissipation may occur would be a bolted connection through an
over-drilled hole.
X2.1.1.2 Test Method A is based on Ref (2), which was
developed by the Structural Engineers Association of Southern
California (SEAOSC) to test wood or steel framed shear walls
for earthquake resistance. The Ref (2) is currently not being
maintained. There is a considerable breadth of information and
vast databases on walls tested under Ref (2). For the purposes
of acceptance testing it would be permissible to correlate the
results of the two test methods.
X2.1.2 Test Method B:
X2.1.2.1 The cyclic protocol for Test Method B was developed for ISO 16670, a method for testing mechanically fastened timber joints. The background for this standard is given
in Ref (3-6), which indicates that a unique cyclic displacement
or loading history will always be a compromise, but one that is
conservative for most practical cases should be selected. The
Test Method B test protocol is intended to produce data that
sufficiently describe elastic and inelastic cyclic properties; and
typical failure mode that is expected in earthquake loading.
X2.1.3 Selection of Test Method A Versus Test Method B :
X2.1.3.1 Test Method A may be applicable to systems when
FME is the yield limit state or for testing slack systems to
determine a lower bound displacement causing hysteretic
energy dissipation. Test Method B is a ramped displacement
phase that bases the cycles on the percentage of an ultimate
displacement determined through static tests. Test Method B
may be more applicable to systems that exhibit linear elastic
5
The boldface numbers in parentheses refer to a list of references at the end of
this standard.
behavior where FME is the strength limit state. If the ratio of
Dm and FME is less than three, Test Method B may be
preferable. Both test methods are intended to generate similar
displacement amplitudes in order to obtain similar number of
points in the envelope curves. The difference is the number of
cycles in each phase (step).
X2.2 Test Method C
X2.2.1 Test Method C (CUREE protocol) is the latest
addition to the family of cyclic test protocols. It was developed
based on the statistical analysis of seismic demands on
light-frame buildings representative of California (in particular
Los Angeles) conditions. The CUREE basic loading history is
a realistic and conservative representation of the cyclic deformation history to which a component of a wood structure likely
is subjected in earthquakes (7, 8). At relatively large deformations (primary cycles exceeding an amplitude of 0.4 D), the
amplitude of the primary cycles increases by large steps. These
large steps are based on statistics of inelastic time history
responses. If the purpose of the experiment is acceptance
testing, then it is permissible to reduce the step size of the
primary cycles with large amplitudes. Smaller step sizes close
to failure may result in a larger capacity (largest amplitude at
which the acceptance criteria are met), even though they will
result in larger cumulative damage. The reason is that the large
step sizes of the basic loading history permit evaluation of
acceptance only at discrete and large amplitude intervals. This
standard permits a reduction in step size only for phases in
which the amplitude of the primary cycle exceeds D. In that
regime the amplitude the primary cycle may be increased by
aD, with a to be chosen by the user, but a # 0.5.
X2.2.2 The reference deformation, D, is a measure of the
deformation capacity (Du) of the specimen when subjected to
the cyclic loading history. It is used to control the loading
history, and therefore needs to be estimated prior to the test.
The estimate can be based on previous experience, the results
of a monotonic test, or a consensus value that may prove to be
useful for comparing tests of different details or configurations.
In CUREE Project (7), the following guidelines were used:
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E2126 – 11
X2.2.2.1 Perform a monotonic test, which provides data on
the monotonic deformation capacity, Dm. This capacity is
defined as the deformation at which the applied load drops, for
the first time, below 80 % of the maximum load that was
applied to the specimen.
X2.2.2.2 Use a specific fraction of Dm, that is, gDm, as the
reference deformation for the basic cyclic load test. At this
time, a value of D = 0.6 Dm is suggested. The factor g should
account for the difference in deformation capacity between
monotonic test and a cyclic test in which cumulative damage
will lead to earlier deterioration in strength.
X3. TEST SETUP
X3.1 CUREE recommendations (9) suggest that top of wall
boundary conditions may influence wall test results. The
weight of the load beam and actuator on a test specimen can
reduce the anchorage demand in a specimen tested in a vertical
orientation. The inertia from a heavy load beam during a cyclic
test will exaggerate the measured response in test frames that
test a wall either vertically or horizontally. For these reasons,
the mass of the load beam and any hydraulics supported by the
specimen shall be minimized to the extent practical. In test
setups where vertical load from the actuator is carried by the
test setup, the impact of the actuator mass may be evidenced by
the difference in the positive and negative response from a
symmetrical system. Test frames have been constructed that do
not impose any vertical load on the specimen. The 350-lbf
(1.56-kN) load limit is based on committee judgment that
considered a range of test frames that are successfully
employed.
X4. COMMENTARY
X4.1 Performance Parameters—It is always permissible to
analyze the positive and negative envelope curves for a
specimen individually and report the corresponding response
parameters without averaging. However, the method for computing average performance parameters that characterize both
envelopes (positive and negative) can make a difference when
a specimen shows an asymmetrical response. In laboratory
practices, the responses from most wall tests are asymmetrical
to some degree as damage created with an initial positive
excursion tends to weaken the response from the subsequent
negative excursion within the same cycle. Determining the
average response parameters for a specimen with dissimilar
positive and negative envelope curves by analyzing each
envelope (positive and negative) individually and then averaging can result in non-conservative estimates of the performance. Therefore, it is the committee judgment that when one
set of parameters is used to summarize the specimen response
for structural design purposes, the parameters should be
calculated from the average envelope as the primary method of
analysis. Using this approach reduces the non-conservatism for
a moderately asymmetric wall. Calculation of average parameters individually from the negative and the positive envelopes
will provide a practical approximation of the average parameters for reasonably symmetric envelopes; that is, if major
events occur in the same phases on the negative and the
positive sides. Caution and judgment should be used in
estimating any form of average response to characterize a
system that is grossly asymmetric. In these instances, the
positive and negative envelopes should always be analyzed and
reported individually without averaging.
X4.2 Number of Tests—Depending on the purpose of a
testing program, the minimum number of tests required in 8.1
may require an adjustment. For example, if the test program is
intended for an exploratory study, the number of tests (two)
specified in 8.1 may be sufficient. On the other hand, if the test
program is intended for code acceptance, three to five replications are typically required by the code evaluation agencies for
a specific specimen configuration.
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E2126 – 11
REFERENCES
(1) Porter, M. L., “Sequential Phased Displacement (SPD) Procedure for
TCCMAR Testing,” Proceedings of Third Meeting of the Joint
Technical Coordinating Committee on Masonry Research, U.S./Japan
Coordinated Earthquake Research Program, Tomamu, Japan, 1987.
(2) Structural Engineers Association of Southern California, Standard
Method of Cyclic Reverse Load Tests for Shear Resistance of Framed
Walls for Buildings, Sacramento, CA, 1997.
(3) Park, R., “Evaluation of Ductility of Structural & Structural Assemblages from Laboratory Testing,” Bulletin of the New Zealand Society
for Earthquake Engineering, Vol 22, No. 3, September 1989.
(4) Chopra, A. K., Dynamics of Structures—Theory and Applications to
Earthquake Engineering,” Prentice-Hall, Inc., Englewood Cliffs, NJ,
1995.
(5) Foliente, G. C., Karacabeyli, E., and Yasumura, M., “International Test
Standards for Joints in Timber Structures under Earthquake and Wind
Loads,” Proceedings of Structural Engineering World Congress, Ref
T222-6, San Francisco, CA, 1998.
(6) Foliente, G. C., and Zacher, E. G., “Performance Tests of Timber
Structural Systems Under Seismic Loads. Analysis, Design, and
Testing of Timber Structures Under Seismic Loads,” Proceedings of
Research Needs Workshop, available from University of California–Berkeley, Forest Products Laboratory, Richmond, CA, 1994.
(7) Krawinkler, H., Parisi, F., Ibarra, L., Ayoub, A., and Medina, R.,
“Development of a Testing Protocol for Wood Frame Structures,”
CUREE Publication No. W-02, 2000.
(8) White, M. W., and Dolan, J. D., “Nonlinear Shear-Wall Analysis,”
ASCE Journal of Structural Engineering, American Society of Civil
Engineers, New York, NY, November 1995.
(9) Cobeen, K, Russell, J., and Dolan, J. D., “Recommendations For
Earthquake Resistance in the Design and Construction of Woodframe
Buildings,” CUREE Publication No. W-30, 2003.
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